A. By default, SCCM uses a self-signed certificate for the PXE communications, which has a configured expiration date. This certificate can be replaced with an alternate certificate, or the expiration date can be changed by opening the Configuration Manager Console, navigating to Site Database, Site Management, , Site Settings, Site Systems, and select the properties of the ConfigMgr PXE service point. Under the Database tab, change the date of the PXE certificate expiration, as shown here.